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The Back The Spine: Vertebrae Number and Function Cervical 7 Supports and moves head Thoracic 12 Support for thorax Lumbar Sacral 5 Support for abdomen 5 fused Transmit weight to lower limbs through pelvic bones Coccygeal Identifying Features Transverse foramen, C1: atlas and C2: axis, small size, bifid spines, Sloped zygapophysial (ZP) joints Uncovertebral joints: between bodies of vertebrae Facets and demifacets for rib articulations, Vertical ZP joints Large body, mammillary processes, “Scotty Dog” from oblique view, Wrapped ZP joints Articulate with pelvis, 4 pairs of sacral foramen (anterior and posterior) Fused into coccyx, no vertebral arches or canal 3-4 fused Spinal Nerves C1-C8 (superior to associated vertebra) T1-T12 (inferior to associated vertebra) L1-L5 (inferior to associated vertebra) S1-S5 (inferior to associated vertebra) Co (inferior to associated vertebra) Superficial Back Muscles: movement of appendicular skeleton Muscle Innervation Accessory nerve, C3-C4 Trapezius Latissimus dorsi Thoracodorsal nerve (C6-8) Levator Scapulae C3-C4 and Dorsal scapular nerve (C4, C5) Dorsal scapular nerve (C4, C5) Dorsal scapular nerve (C4, C5) Rhomboid Major Rhomboid Minor Function Rotate scapula in arm abduction beyond horizontal; elevate, adduct, and depress scapula Extends, adducts, and medially rotates humerus Elevate scapula Retracts and elevates scapula Retracts and elevates scapula Intermediate Back Muscles: respiratory function Muscle Serratus posterior superior Serratus posterior inferior Innervation T2 to T5 T9 to T12 Function Elevate ribs 2 to 5 Depress ribs 9 to 12 Deep Back Muscles: intrinsic muscles that move the head/neck and vertebral column Group Muscle Spinotransversales Splenius capitis Splenius cervicis Erector Spinae Iliocostalis Longissimus Spinalis Transversospinales Semispinalis Multifidus Rotatores Segmental Levatores Costarum Interspinales Intertransversarii Suboccipital: all innervated by C1 Rectus capitis posterior major Rectus capitis posterior minor Attachments Lower ligamentum nuchae, spinous processes C7-T4; mastoid process Spinous processes T3 to T6; Transverse processes C1 to C3 Common tendon of origin, lower ribs; upper ribs, lower cervical vertebrae Common tendon of origin; base of skull Interconnects spinous processes of adjacent vertebrae Lower thoracic region; back of skull, crossing between 4 and 6 vertebrae Pass from lateral insertions upward and medially to spinous processes, spanning 2 to 4 vertebrae Transverse processes to spinous processes, crossing 2 vertebrae (long) or attaching to adjacent vertebrae (short) Transverse process to rib below Between spinous process on each side of interspinous ligament Between transverse processes Spinous process of C2 to lateral occipital bone below inferior nuchal line Posterior tubercle of C1 to medial occipital bone Function Extend neck, rotate head to same side Extend neck, rotate head to same side Major extensor of vertebral column and head, lateral flexion Major extensor of vertebral column and head, lateral flexion Major extensor of vertebral column and head, lateral flexion Extension and rotation of vertebral column Extension and rotation of vertebral column Extension and rotation of vertebral column Elevates rib Postural-stabilization Postural-stabilization Extend head, rotate face to same side as muscle Extend head Obliquus capitis superior Obliquus capitis inferior below inferior nuchal line Transverse process of C1 to occipital bone between superior and inferior nuchal lines Spinous process of C2 to transverse process of C1 Extend head, bends it to same side Rotates face to same side *Suboccipital Triangle: borders made up by rectus capitis posterior major, obliquus capitis superior, and obliquus capitis inferior. The triangle contains the posterior ramus of C1, the vertebral artery, and associated veins *Spinal Cord: from foramen magnum to L1 or 2 (conus medullaris), Subarachnoid space ends at S2 Meninges: Meninges Location Structure Dura Mater Outermost Thick, fibrous Arachnoid Mater Middle Thin, delicate, contains blood vessels Pia Mater Innermost Vascular membrane adhered to surface of spinal cord Significance Becomes epineurium of spinal nerves and their roots Subarachnoid space (b/t arachnoid and pia) contains CSF Forms denticulate ligaments that extend laterally from the cord toward the arachnoid and dura, anchoring the spinal cord in place *Spinal Nerves: 31 pairs, each is connected to the spinal cord by anterior roots (motor nerve fibers) and posterior roots (sensory neuron processes, whose cell bodies are located in spinal ganglion). Spinal nerves exit the intervertebral foramen and branch into posterior rami (innervate intrinsic back muscles and the dermatomes of the back) and anterior rami (innervates most other muscles of the body and the remaining portions of skin). * Curvatures of Spine: - Primary (concave anteriorly): Thoracic, Sacral/Coccygeal - Secondary (concave posteriorly): Cervical, Lumbar * Identify: Bones, Ligaments of Vertebral Column, Intrinsic and Extrinsic Muscles of Back, Vasculature of Back, Spinal Cord and associated Spinal Nerves and Branches, Meningeal Layers, Surface Anatomy Clinical Considerations Injury/Disorder Spina Bifida Occulta Patient Presentation Tuft of hair over spinous processes Anatomy Involved Vertebral arches (usually lumbar) Abnormal lateral curvature in spine Vertebrae tend to be normal in structure but are abnormally aligned or rotated Scoliosis Kyphosis: thoracic region (humpback) Lordosis: lumbar region Herniated Disc Spinal Stenosis Pars Interarticularis Fracture Back pain, loss of motor/sensation in area of body Loss of motor/sensory capabilities Fracture of ZP joint causing vertebrae to slip anteriorly and compress the vertebral canal Mechanism of Injury Developmental- failure of fusion in posterior arches of vertebrae Congenital, idiopathic, nerve abnormalities (cerebral palsy, polio), muscular dystrophy, tumors and disc protrusions Tear in anulus fibrosis allowing nucleus pulposis to seep. Intervertebral disks, spinal cord or spinal roots or nerves Degeneration of annulus fibrosis Ligament flava, zygapophysial joints, intervertebral discs Dimensions of the vertebral canal are reduced by hypertrophy or degeneration of surrounding structures Superior and inferior facets making up the ZP joints, usually L4-5 Trauma, common in athletes